The density of iron is 7.87 g/cm3, and the average mass for one iron atom is 9.28×10-23 g.

Question

How many atoms are there in a rectangular iron ingot measuring 3.00 cm × 3.00 cm × 9.00 cm?

Answer 1

you want to convert volume to #atoms. SO, start plugging in your conversion factors:

3.00cm*3.00cm*9.00cm = 81cm^3 * 7.87g/cm^3 / 9.28*10^-23g/atom = 6.87*10^24 atoms